Yes. The Golden Pass is a train route, not a pass or ticket. You can buy a ticket from Interlaken to Montreux and get a 50% discount with a Swiss Half Fare Card. The Swiss Half Fare Card does not have a class. You can use it to buy either first class or second class tickets.

When using the timetable to find a suitable departure time, put "Zweisimmen" as a via station to get the Golden Pass route. Otherwise the timetable will show you the faster routes via Visp or Bern.

The sector of the Golden Pass route between Zweisimmen and Montreux can get pretty busy, so reservations are a good idea. You can make them at the site below. There are no discounts on the reservation fee.